We're here at the Polk County Transportation a vision we're going to take
a look to see how the traffic flow is managed back relax and join us on the science
.
Hey we try I mean with Amy the traffic manager for Polk County Amy tell me
a little bit about what you do here while we take care of two hundred in seventy
two signals for the entire county with the exception of the signals in
a city like Lindsay Winter Haven so we have
a big responsibility with traffic signals. Some of those are on state road some of
them are in other cities we have eighty seven of our own signals on county roads
and four those were also responsible to do the signal timings and some of those are
individual time some of them are coordinated traffic signals and do you regulate
that I mean you do plan all that ahead of time is it on the fly is it how does it
work and you know it's kind of case by case when
a new traffic so much goes in we collect traffic data and the timings are based on
the traffic flows on the two roads. We also periodically look at them if we get
a complaint from a citizen if we haven't looked at a signal in
a number of years we'll see if the traffic has changed over time and if any
adjustments need to be made to those timings and what's the purpose or objective of
all this timing the purpose is to get the most efficient flow of traffic we want to
make sure primarily that the major road gets the appropriate amount of time to get
traffic moving through our major corridors and then still provide time for the side
streets to be able to get out and heavy traffic. When we have several signals that
are close together and that's that's more urbanized areas then we're able to
coordinate those times so that one signal will turn in the next one will turn and
you can have
a steady progression of traffic now when you say you regulate in the manage the
timing can you do all that here or how does that work we can't do all of it here
some of it we have to do in the field but we are able to adjust about
a third of our traffic signals from our Traffic Management Center and we can go see
Mike my network analyst and I'll show you how that gets done also will go up.
In my house a guy he sent me this way said you could give me
a little background on as to how you control everything how you can manage and see
it from the cameras and stuff like that all right this is our C.M.C.
And we have ninety three intersections that we can communicate with. That our
central software is up here and that tells us everything that we need to be able to
tell from the controller. Anything that we can do from the field. That's not
mechanical we can do from mere facts logic base we can run it through the computer
OK And you can access I see several streets I'm familiar with you can access all
those just right here in C.
Then at different times or we have
a twenty cameras on our system and of those we can bring them up and we can pan
tilt zoom and we can be able to troubleshoot anything that comes in immediately as
it happens rather than have to send somebody out there if it's an hour away the
conditions may have changed by the time we get to it so this helps us immensely
with the response time and I'm guessing you can just sort of. Focus in on just one
camera see if that's where your problem areas we can the screens we can adjust you
know however we need to we can fit more of them on there make it smaller is to get
more of them on there so you can have one if you're primarily concerned with one
specific incident you can bring one up there and make sure you can get
a good picture of what you're trying to find Now how many cameras do you usually
have it's not an idea of one facing every direction or is it just one that you
control and turning around as you please for these cameras it's just one dome
camera on one of the corner so that usually is the cabinet corners or wherever we
can get the best visibility out of it now looking at video from all over the county
it looks like how do you receive this information is it just Internet we have
a couple different transmission methods that we use for getting only for mission
back here we use fiber where we can get it and that would be ideal but one of the
big challenges of full county is we're so spread out and we aren't close like
a lot of the municipalities we cover all of unincorporated. So on the locations
that we can get fiber we would love that if we can't we use different ways to get
it back here we have some radio shops and some of these camera feeds are coming
over radio and they do just fine for what we need and for we also have some air
cards as well that will allow us to talk to some of the controllers but they're not
powerful enough to bring any kind of video feed OK. Now I know that some of the the
lights are regulated here how do you determine which ones get sent back here we try
to get as many as we can under our system and obviously we don't have them all yet
. But we already talked about the different controllers the older technology in the
newer technology only the newer ones can communicate back to the system anyway so
as we upgrade those older systems we also look at communicating with them at that
time and how do we get that back to here so we try to get as much as possible if
there are clustered together we can try and get as many one time that we can get OK
now I've been I've been on some roads and I've noticed that you hit it just right
and you get the greens just all the way you guys have
a part and that is part of the chord in that system and that is something that we
manage from here. When it shows that it's in coordination and it's in sync you'll
get that good flow occasionally though they do get out of sync and that's one of
the things that we can handle as well OK And how do you handle that you just
a little bit of reprogramming or there's different methods of getting them back in
sync you can go a little bit shorter
a little bit long. The reason they get out of sync is
a lot of times you'll have pedestrian come up on the side and they need
a lot of time to be able to walk and the Don't Walk the clearance time for them as
well and another issue is an ambulance or
a police officer will come through that also in
a coordinated system off as they travel through it or even
a train that comes up as well now I'm
a C N N On this map here with all the other little dots is this I sort of keep an
eye on them to see if they're in sync or out of sync or it is there's several
coordinated systems through ways on here. And even some of them changed or six in
this one includes some of like when and some for county and it doesn't matter who's
system is on as long as it's time based they will sing together so they run pretty
smoothly they're going to wear. Now is there anything else you you can control and
here you program in here other than just the sinking of the lights we can with
a lot of the newer technology we can bring the detection methods and. Everything
back into here one of those
a video detection. And we bring that up in here to map out zones that we don't want
anything interfering with the detection and we don't want you know shadows and
trees and things to negatively affect the intersection and that's one of the
technologies that he's going to talk about in our signal. So
Amy I'm seeing a lot of equipment here there seems to be
a lot of stuff that goes into this can you give me
a little explanation as to what it is sir this is pretty much the brains behind the
whole traffic signal operation you'll see
a cabinet like this and pretty much it every signal is intersection it might be
different we've got some tall skinny ones but this is basically the computer that
operates the signal and all the timings right now I see a lot
a lot of technology in here is it always been this way now years ago traffic
signals were operated by a a mechanical system that only could have
a fixed time so there was a certain time for the main road
a certain time for the side road but now we have computerized equipment that we can
adjust times based on the vehicles that are coming so. The controllers smart enough
to know if there's more traffic it's able to give more time to the main street and
if there's no traffic on the main road it'll switch to the side road so that it's
it's gotten
a lot smarter over the years now what is this why don't contrivance you appear it
looks like
a street with actual lights is this what's happening right now because this
controller actually we can test
a controller before we put it out in the field so this hooks up to this board and
the board looks just like it would operate out in
a traffic signal in the field so the lights as you see him changing that's how they
change based on the times are programmed in this controller right. Now OK So this
is it in this is what's actually in those boxes were it is life it is very cool All
right so this is the brains of the operation what are some of the other parts of
the systems I mean what all does it control obviously the law is but how does that
all can measure Well this is the traffic you know this is the computer but there
has detectors that actually receives information from. From the traffic that's
coming we have different ways to detect traffic either inductive loops that are cut
in the ground you may see
a big circle in the pavement where you stop your vehicle that's an inductive loop
it works sort of like a magnet and can tell if
a car's there we also use video detection so we have cameras that can tell us if
the car's there so that it takes that information it knows the car's there and it
feeds it to the computer to tell the controller what to do with the with the
traffic signal OK And so I see that. Turn signals obviously I see that all the time
. Does that control the pacing too I mean if there's
a lot of cars. Depending on the amount of traffic it is able to we have
a minimum time set for how much green time you're going to be allowed but there's
also
a maximum time so if there are traffic vehicles that continue to come it's able to
extend that minimum green time to give more time to accommodate the traffic that's
coming if there's
a break in traffic that it's going to tell the controller we don't need any more
green time and they'll turn it to yellow and then red and then the side street gets
its turn and that's only if there's
a car on the side street if there's no cars on the side street it'll stay in green
for the main road indefinitely now you talk about minimum green time so what about
the yellow light I notice that sometimes it. Seems
a little quicker than other times and the yellow time is based on the speed of the
approach road so for high speed traffic you might have four or five seconds of
yellow for
a thirty five. Mile an hour road it might only be three seconds but yeah the yellow
time does vary based on the type of roadway that the traffic signals so it's
already doing now you mention there's some different types of detection the
inductive in the camera What are some advantages of one over the other video
detection is easy to use it's. Easier to work
on the loops or in the pavement so if you have to do any work on the pavement you
have to close a lane of traffic it's a it's
a lot more effort to take care of if something goes wrong and something can go
wrong if the pavement is old then the loop may start coming out of the ground or or
break so you can have some problems with maintenance video detection can have
problems in the fog or shadows because they see movement and that it thinks it's
a vehicle so if you have a tree nearby that causes a shadow It may think it's
a vehicle and you might get in might be calling traffic when it doesn't really need
to so you know there are benefits and disadvantages to both types of technology we
use them both now my friend always tells me that white always ignores him is that
true is there
a difference shouldn't I know that you can adjust the sensitivity of the loop
that's in the ground but
a motorcycle has enough metal to it it should it should recognize that it's there
certainly video camera should be able to see it so that shouldn't be the case if we
get that type of complaint we can certainly go look at it and see if the
sensitivity needs to be adjusting We also have similar problems with long trailers
that may have not metal on the trailer but it might be wood and if it's not
a significant metal it might have
a little more difficulty picking it up but again we should be able to adjust the
sensitivity so that's not an issue and how far back from the from the stop line we
were supposed to stop how far back is the inductive loop usually going to be it's
usually
a couple feet behind the stop bar but it's it should be able to. You know if you
pull up past
a stop are it should still pick you up if your way in front of the STOP are there
are times when it won't catch you. So that's why we have the stop are it tells you
where to stop and generally yeah the loop is
a couple feet behind that stop learning should cover
a pretty good range of where folks stop now what are these some of the approximate
costs for these intersections Well there's
a couple different type of intersection you might see. What we've had for many many
years our spanners employees you'll see. Probably four concrete poles and
a gender section that have just
a wire running between with the signal heads on and we call that
a span wire assembly and that's maybe on the order of eighty thousand dollars per
intersection we also have massed arms which are bigger metal structures with big
arms they're about twice the cost maybe
a hundred sixty thousand dollars per intersection part of that's
a static it is more structurally sound it's you certainly want to mirror
a cosigner or you have hurricane force winds that's not as important in Polk County
would be in the southern state but you know they look nice so some maintaining
agencies in certain corridors want you know more aesthetic looks but both of them
function the same for as far as traffic signals and it with obviously with the
growth of the county and the growth of the area when you guys determine there how
do you determine when to put in a new light or to put in
a new intersection Well you know it's based on traffic and traffic needs when we
see that there's an intersection that is approaching you know heavy volumes we
would look at if we have warrants for traffic signals and we're always looking at
the road network and the traffic volumes to improve traffic flow so we're always
keeping an eye on on the traffic to see what improvements we might need to make and
fact the traffic changes impact
a lot of what we do it's part of this division for instance bridges are impacted by
changes in traffic and when they might need to be updated or rebuilt and boy or
a structural engineer I think is ready to talk to about bridges. Or looking over
a I'm with keen
a structural engineer for Polk County can let's start off with the main question
what is a bridge bridge is structurally used to go from one side of
a road or obstacle to another without interfering with the obstacle and what types
of bridges are there. Many types three basic materials that we were with
concrete steel and wood in certain cases and each material then
you get into different design types and beams and. Elements of the bridge and when
you say design types I mean I know this isn't the only style of bridge what are
what are some of the what are some examples Well the in steel you use says we just
have you can have your steel trusses which are much larger structures. The elements
are essentially just made out of steel this bridge here is
a concrete bridge it's pre-stressed beams I believe and it's
a prefabricated beam Also you can actually do cast in place which means you
actually make the forms in place and pour the concrete in place and take forms and
go away and what what goes into this terming you know what the look of the bridge
is going to be like. Economics is always a factor you have
a static reasons you want to do something and then certain bridges are inexpensive
to build quick an easy and entirely durable like
a casting place is one of the basics but the span this span that we have here is
about. Thirty feet so that helps determine what type of bridge is bigger bridges
longer span different elements different beam style sizes and styles how far apart
when you say big or bridge and stuff about what's the rule of thumb for pilots is
their rules for how where the supports are going to be or how does that work out
that's those are design issues the actual design or make those determinations of.
No real rule of thumb is just the longer this man the bigger the beams and the
bigger the pile and bigger everything or the new Like the largest one of course of
the suspension bridges like the cable stays or the Golden Gate We don't have
a need for those around here we don't have any rivers quite that big band are there
any special preparations you do I know we're in Florida hurricanes
a lot of storms and something or other special preparations you do special
procedures you have for for building the bridge or to help it withstand those. What
you just describe are just. Different loads in
a long list of loads you know the one thing the bow bridges they are designed to
carry traffic loads which is your cars and trucks and buses and and cranes and
anything else that goes on the road motorcycles and bicycles also. The hurricane
is gives you the win load in the else have water loads water is
a load it rises and falls and it can be quite severe sometimes given the hurricane
load as is is brings the wind in the rain and it's just. Several of the
long list of lows that we have to deal with and. One that we see
mostly is
a flood issue and flood is rising waters century by definition it's not really rain
coming down the rising water and so on canals and creek and road crossings they
may or may not get clogged fellow bridges bigger the bridges get
a larger opening the smaller ones. From my dog standpoint you might build
a culvert will be called
a culvert which is they're essentially relatively speaking small they might be
eight to ten feet wide or several We call them barrel several openings the problem
that they have is large flows they tend to collect dirt and trash and debris trash
bin you know trees and sticks and everything and the sediment will build up and
they do tend to clog a lot quicker than
a bridge will go and what do you how do you maintain or how do you maintain that
the coverts basically just have to go in clean amount. You know with machinery or
man or
a little bit of both and somebody might have to get what is there as their regular
schedule or is it you have an extra inspector goes around and check the bridges are
and how that works well the bridges if it's there on the bridge lifts you know by
definition a bridge is twenty feet from side to side they're on
a regular two year inspection program and. The reports indicate if there's an
issue and we go out and check
a mountain if there's an issue we. Face public safety is
a big thing we provide the for public safety the traveling public and if it becomes
a safety issue we take care of it right away regular maintenance is regular
maintenance you know they. Trash and debris cumulate so you can. That clean it up
when you when it's on your schedule to do so all right. Now tell me
a little bit about the the design of this specific bridge that we're staying here
just so I can get a better understanding of how
a bridge going with the canal wouldn't wait it would get put in OK. Well this
bridge it's basically thirty feet from side to side. It was it's been here since
about one thousand nine hundred eighty the this canal actually provides for boat
traffic so another factor we have to consider is. Make sure there's enough water in
here for
a boat to pass because they do fill in and you have to dredge and. Once you set the
span the design will start to span cording the criteria given by the canal boat for
the traffic requirements and then you can calculate loads in that you know each
element has its own capacity so you design you choose
a number of like piles you see the piles underneath on each side you choose
a number of those based on each capacity and we also have to do
a geotechnical investigation which means we send in another engineer different kind
of engineer and he actually drilled
a hole probably about eighty five feet deep to find out what kind of soil is
underneath where we're standing up because that's what we're going to use to hold
the bridge up and it is the obviously you can't really get rid of the water you
just have to deal with the added work around that well in this bridge and we did
all this work. There was no boat traffic because we dam that can now OK so about
where I we were standing we had
a twenty foot. Tall polished dirt and some sheet piles to block off the water so
the guys when they're working we're actually working in the dry OK under certain
conditions you can do that other conditions you just have to work in the water all
right now I know obviously with the water here and stuff it's going to erode away
and it's going to cause some deterioration and what goes into an inspection for
a bridge like this to make sure that it's still you know that stable OK well this
bridge is
a small bridge but amazingly enough it does have all the parts and so on and since
we're over canal and see the canal here. Water is very corrosive believe it or not
and it will dissolve anything and everything in the inspection with water here we
would actually send divers out and they would go down to the bottom of the canal
and look at the elements are actually in the water and in our case we have the
concrete piles and this deal back wall which is the black that you see.
And we also have a boat coming through and the boat actually creates
a force on the bridge also. Now speaking of loads there's obviously in the news
you've been reporting the stuff about some bridges being structurally deficient How
do you go about rating those and determining when they need maintenance or how
serious the maintenance is going to be well the those terms in the ratings actually
come out of the inspections the the the regular inspections and. The structural
deficiency is
a reflection of the capacity of the bridge to still do its job which is carry
traffic across the obstacle safely to the. You lose your
sufficiency by deteriorating you know concrete gets old and soft and the steel
inside will rust and cause you know problems with the bridge you know regular steel
bridges steel itself or ROSS You know I mean it's on the steel bridge is clean and
painting on a regular basis and so it is a it's actually
a calculated number and you can recalculate the capacity of the beam or the
bridge in its new condition as opposed to its use condition you know new condition
be in thirty to forty years after it was built it's
a current condition that we're in and that's what we look at for the repairs and
what's wrong with the bridge and can this repair extend the life of the bridge or
at some point we actually do evaluation do we need to just replace the bridge
rather than continue to spend money to fix an old tired bridge now you mention with
the main maintaining the steel bridges it repainting in and helping take care of
some of that rust and stuff is there anything special you do to help prolong the
life of
a concrete bridge. Nothing not that obviously simple but essentially we do the same
thing we can you know concrete you'll notice they get black and everything else
just mold and stuff so we we can actually come in and clean and paint and the pain
acts as
a SEAL or what deteriorates bridges rapidly relatively speaking is again it's water
whether it's rain water or sea water or whatever kind of water and
a good concrete is not waterproof so it water will penetrate and this get to the
steel in the steel will eventually rust and so we clean and paint that helps us we
mostly with concrete you seal it if it has broken areas where it's cracked and
stuff you chip off the loose concrete you can we have high tech mortars and stuff
that will stick and seal it back off and we essentially just packed it all right so
obviously you can maintain it above but I know
a lot of the bridge is underneath is down the water you know right there where the
water is how hot how do you help prolong it well same idea
in on this bridge you can see along the side there's the five red squares those are
the piles and what we did in this case the piles have been sitting in the water for
however long twenty to thirty years and as I said before water is extremely
corrosive and so what we do with the piles is we essentially come just put
a jacket around them and that's where you see the larger part and then the very
small part of the top is the original pile the larger part of it is just like you
putting on
a jacket because it's cold out we put jackets on here to keep the water off of the
structural part of the pile and the black wall behind the piles. In this bridge
that was entirely replaced because it used to be. New Porsche
a new steel that was essentially rusted through several spots and it could no
longer hold the soil up behind it those are all new and we coat the steel with
a coating just to stop it from rusting and it will that what we did here is
a it has
a design life not intended to last forever but it'll be fifty sixty years before we
have to actually come out and give it some serious attention again because now I
notice on this bridge there's a there's
a drain popping Elo What's that go to with that help out with OK Well those are.
You referring to though P.V.C.
Pipe sticking out through the walls Those are just drains because we don't want
water to build up behind the wall because if the water builds up that's
a tremendous load on the wall and it also would tend to wash with the dirt out from
behind us so we put drains into. The tent of the storm is hydrostatic pressure we
put the drains in to relieve the hydrostatic pressure tank and so the small simple
but very important now obviously we talk about maintaining the bridges about how
many bridges throughout the county do you have to take care of are you responsible
for while I take care of the Polk County bridges that Polk County actually owns
many bridges are owned by the state but the Polk County is the proud owner of about
one hundred eighty four bridges and it varies because we're building new ones on
occasion we actually tear one or two down the no longer necessary and there's
another way that they can go. It's quite
a number of bridges the good thing is most if not all are in generally good shape
you get
a good well thank you so much for bringing out here let me know your brain about
the bridges was my pleasure Brad thank you well that's all we have for today join
us next time as we see got yet another science question.